1、查看centos 版本：cat /etc/redhat-release
2、启动服务：systemctl start firewalld.service
如果服务报错Failed to start firewalld.service: Unit is masked
执行systemctl unmask firewalld.service
再启动 systemctl start firewalld.service
3、关闭服务：systemctl stop firewalld.service
4、重启服务：systemctl restart firewalld.service
5、显示服务的状态：systemctl status firewalld.service
6、在开机时启用/关闭服务
systemctl enable firewalld.service
systemctl disable firewalld.service
7、查看已启动的服务列表
systemctl list-unit-files|grep enabled
8、停止 firewalld
# systemctl stop firewalld
# systemctl mask firewalld
